A quantitative model using multi-parameters in dual-energy CT to preoperatively predict serosal invasion in locally advanced gastric cancer

OBJECTIVES

To develop and validate a quantitative model for predicting serosal invasion based on multi-parameters in preoperative dual-energy CT (DECT).

MATERIALS AND METHODS

A total of 342 LAGC patients who underwent gastrectomy and DECT from six centers were divided into one training cohort (TC), and two validation cohorts (VCs). Dual-phase enhanced DECT-derived iodine concentration (IC), water concentration, and monochromatic attenuation of lesions, along with clinical information, were measured and collected. The independent predictors among these characteristics for serosal invasion were screened with Spearman correlation analysis and logistic regression (LR) analysis. A quantitative model was developed based on LR classifier with fivefold cross-validation for predicting the serosal invasion in LAGC. We comprehensively tested the model and investigated its value in survival analysis.

RESULTS

A quantitative model was established using IC, 70 keV, 100 keV monochromatic attenuations in the venous phase, and CT-reported T4a, which were independent predictors of serosal invasion. The proposed model had the area-under-the-curve (AUC) values of 0.889 for TC and 0.860 and 0.837 for VCs. Subgroup analysis showed that the model could well discriminate T3 from T4a groups, and T2 from T4a groups in all cohorts (all p < 0.001). Besides, disease-free survival (DFS) (TC, p = 0.015; and VC1, p = 0.043) could be stratified using this quantitative model.

CONCLUSION

The proposed quantitative model using multi-parameters in DECT accurately predicts serosal invasion for LAGC and showed a significant correlation with the DFS of patients.

CRITICAL RELEVANCE STATEMENT

This quantitative model from dual-energy CT is a useful tool for predicting the serosal invasion of locally advanced gastric cancer.

KEY POINTS

Serosal invasion is a poor prognostic factor in locally advanced gastric cancer that may be predicted by DECT. DECT quantitative model for predicting serosal invasion was significantly and positively correlated with pathologic T stages. This quantitative model was associated with patient postoperative disease-free survival.

Dorsal approach for advanced gastric cancer invading the transverse mesocolon

Minimally invasive gastrectomy is increasingly performed for advanced gastric cancer, but the indication for this procedure for a tumor invading adjacent structures is still limited. In cases with tumors invading the transverse mesocolon, a large tumor together with the involved mesocolon blocks the surgical view, which prevents evaluation of the extent of invasion and makes it difficult to ensure oncologically adequate resection. To solve these technical issues, we established a novel method that uses a dorsal approach. By approaching the transverse mesocolon from the dorsal side, tumor penetration and involvement of the colic vessels or pancreas can be evaluated, and margin-free resection of the tumor becomes easier. In a series of 13 patients with mesocolon invasion, a dorsal approach enabled minimally invasive margin-free resection in 11 cases by resection of the anterior layer of the mesocolon (n = 6); enucleation of the mesocolon (n = 4); or enucleation plus distal pancreato-splenectomy (n = 1). Two patients with broad invasion that obstructed the view underwent combined colectomy by open conversion. A major postoperative complication of pancreatic fistula following distal pancreatectomy occurred in one case. These results suggest that a dorsal approach may be useful for minimally invasive combined resection of gastric cancer invading the transverse mesocolon.

Added Value of the Sliding Sign on Right Down Decubitus CT for Determining Adjacent Organ Invasion in Patients with Advanced Gastric Cancer

Purpose

To investigate the added value of right down decubitus (RDD) CT when determining adjacent organ invasion in cases of advanced gastric cancer (AGC).

Materials and Methods

A total of 728 patients with pathologically confirmed T4a (pT4a), surgically confirmed T4b (sT4b), or pathologically confirmed T4b (pT4b) AGCs who underwent dedicated stomach-protocol CT, including imaging of the left posterior oblique (LPO) and RDD positions, were included in this study. Two radiologists scored the T stage of AGCs using a 5-point scale on LPO CT with and without RDD CT at 2-week intervals and recorded the presence of "sliding sign" in the tumors and adjacent organs and compared its incidence of appearance.

Results

A total of 564 patients (77.4%) were diagnosed with pT4a, whereas 65 (8.9%) and 99 (13.6%) patients were diagnosed with pT4b and sT4b, respectively. When RDD CT was performed additionally, both reviewers deemed that the area under the curve (AUC) for differentiating T4b from T4a increased (p < 0.001). According to both reviewers, the AUC for differentiating T4b with pancreatic invasion from T4a increased in the subgroup analysis (p < 0.050). Interobserver agreement improved from fair to moderate (weighted kappa value, 0.296-0.444).

Conclusion

RDD CT provides additional value compared to LPO CT images alone for determining adjacent organ invasion in patients with AGC due to their increased AUC values and improved interobserver agreement.

The Value of Predicting Human Epidermal Growth Factor Receptor 2 Status in Adenocarcinoma of the Esophagogastric Junction on CT-Based Radiomics Nomogram

Purpose

We developed and validated a CT-based radiomics nomogram to predict HER2 status in patients with adenocarcinoma of esophagogastric junction (AEG).

Method

A total of 101 patients with HER2-positive (n=46) and HER2-negative (n=55) esophagogastric junction adenocarcinoma (AEG) were retrospectively analyzed. They were then randomly divided into a training cohort (n=70) and a verification cohort (n=31). The radiomics features were obtained from the portal phase of the CT enhanced scan. We used the least absolute shrinkage and selection operator (LASSO) logistic regression method to select the best radiomics features in the training cohort, combined them linearly, and used the radiomics signature formula to calculate the radiomics score (Rad-score) of each AEG patient. A multivariable logistic regression method was applied to develop a prediction model that incorporated the radiomics signature and independent risk predictors. The prediction performance of the nomogram was evaluated using the training and validation cohorts.

Result

In the training (P<0.001) and verification groups (P<0.001), the radiomics signature combined with seven radiomics features was significantly correlated with HER2 status. The nomogram composed of CT-reported T stage and radiomics signature showed very good predictive performance for HER2 status. The area under the curve (AUC) of the training cohort was 0.946 (95% CI: 0.919–0.973), and that of the validation group was 0.903 (95% CI: 0.847–0.959). The calibration curve of the radiomics nomogram showed a good degree of calibration. Decision-curve analysis revealed that the radiomics nomogram was useful.

Conclusion

The nomogram CT-based radiomics signature combined with CT-reported T stage can better predict the HER2 status of AEG before surgery. It can be used as a non-invasive prediction tool for HER2 status and is expected to guide clinical treatment decisions in clinical practice, and it can assist in the formulation of individualized treatment plans.

Adrenal Nodules Detected at Staging CT in Patients with Resectable Gastric Cancers Have a Low Incidence of Malignancy

Background Guidelines recommending additional imaging for adrenal nodules lack relevant epidemiologic evidence. Purpose To measure the prevalence of adrenal nodules detected at staging CT in patients with potentially resectable gastric cancer and the proportion of patients with malignant nodules among them. Materials and Methods This retrospective study included 10 250 consecutive patients (median age, 63 years; interquartile range, 53-71 years; 6884 men) who underwent staging CT and had potentially resectable gastric cancer in a tertiary center (May 2003 to December 2018). All 10 250 CT studies were retrospectively reviewed, and patients with adrenal nodules (or thickening ≥10 mm) were identified to measure the prevalence of adrenal nodules. Among patients with adrenal nodules, the per-patient proportions of malignant nodules, adrenal metastasis from gastric cancer, and additional adrenal examinations were measured. A secondary analysis was performed by using data from the original CT reports. The same metrics that were used in the retrospective review were assessed. Results The prevalence of adrenal nodules was 4.5% (95% CI: 4.1, 4.9; 462 of 10 250). The proportions of malignant nodules and adrenal metastasis from gastric cancer were 0.4% ( 95% CI: 0.1, 1.6; two of 462) and 0% (95% CI: 0.0, 0.8; 0 of 462), respectively. A total of 27% of the patients (95% CI: 23, 31; 123 of 462) underwent additional adrenal examination. According to original CT reports, the prevalence of adrenal nodules and the proportions of malignant nodules, adrenal metastases from gastric cancer, and additional adrenal examination were 2.7% (95% CI: 2.4, 3.0; 272 of 10 250), 0.7% (95% CI: 0.1, 2.6; two of 272), 0% (95% CI: 0.0, 1.4; 0 of 272), and 42.6% (95% CI: 36.7, 48.8; 116 of 272), respectively. Conclusion Although adrenal nodules were detected frequently on staging CT images of patients with otherwise resectable gastric cancer, these nodules were rarely malignant. ©RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Baumgarten in this issue.

Establishment of the Radiologic Tumor Invasion Index Based on Radiomics Splenic Features and Clinical Factors to Predict Serous Invasion of Gastric Cancer

Background

Currently, there are shortcomings in diagnosing gastric cancer with or without serous invasion, making it difficult for patients to receive appropriate treatment. Therefore, we aimed to develop a radiomic nomogram for preoperative identification of serosal invasion.

Methods

We selected 315 patients with gastric cancer, confirmed by pathology, and randomly divided them into two groups: the training group (189 patients) and the verification group (126 patients). We obtained patient splenic imaging data for the training group. A p-value of <0.05 was considered significant for features that were selected for lasso regression. Eight features were chosen to construct a serous invasion prediction model. Patients were divided into high- and low-risk groups according to the radiologic tumor invasion risk score. Subsequently, univariate and multivariate regression analyses were performed with other invasion-related factors to establish a visual combined prediction model.

Results

The diagnostic accuracy of the radiologic tumor invasion score was consistent in the training and verification groups (p<0.001 and p=0.009, respectively). Univariate and multivariate analyses of invasion risk factors revealed that the radiologic tumor invasion index (p=0.002), preoperative hemoglobin <100 (p=0.042), and the platelet and lymphocyte ratio <92.8 (p=0.031) were independent risk factors for serosal invasion in the training cohort. The prediction model based on the three indexes accurately predicted the serosal invasion risk with an area under the curve of 0.884 in the training cohort and 0.837 in the testing cohort.

Conclusions

Radiological tumor invasion index based on splenic imaging combined with other factors accurately predicts serosal invasion of gastric cancer, increases diagnostic precision for the most effective treatment, and is time-efficient.

An investigation on gastric cancer staging using CT structured report

OBJECTIVE

To evaluate the clinical performance of structured report (SR) for CT in patients with pre-operative staging of gastric cancer, compared to non-SR.

METHODS

Retrospectively, 51 consecutive cases with primary gastric cancer staging were enrolled. Every SR or non-SR was performed by two GI radiologists (1 junior and 1 senior). Interobserver agreement was conducted between the junior and senior groups for both SR and non-SR. 10 key features required for lesion description and staging were assessed between SR and non-SR. Diagnostic content between SR and non-SR was also compared. Accuracy of SR and non-SR on T staging was measured. Subjective evaluation of SR vs. non-SR was also conducted in form of survey by 20 radiologists and 3 GI surgeons.

RESULTS

Interobserver agreement showed excellent in SR (Kappa = 1, P < 0.001), but poor in non-SR (Kappa = 0.036, P = 0.455). For the 10 key features required for lesion assessment, non-SR showed 6.84 ± 0.83 while SR reported all of them (P < 0.001). Statistically significant improvement was observed in the SR for parts of key features, especially for assessment of adjacent organs and vessels (P < 0.001). Accuracy comparison of T staging showed higher in SR for cohort of T4a (P = 0.028<0.05). The scores of subjective evaluation were higher (P < 0.05) in SR than in non-SR by both radiologists and surgeons. Meanwhile, the inter-observer agreement among surgeons was good in SR with significance (w=0.53, P = 0.005 for efficiency; w=0.638, P < 0.001 for integrity) but poor in non-SR.

CONCLUSIONS

SR of gastric multiphasic CT ensured reliable detection of all relevant key features for staging along with reproducible documentation, which was not always the case for non-SR. In addition, SR has the potential in improving diagnostical accuracy of T staging and was welcomed by clinicians.

Contribution of DECT in detecting serosal invasion of gastric cancer

Background/aim

This study aimed to investigate the relationship between the iodine concentration (IC) of perigastric fat tissue as assessed by dual-energy computed tomography (DECT) and serosal invasion of gastric cancer.

Materials and methods

A total of 41 patients underwent preoperative staging evaluation for gastric cancer using DECT between July 2015 and March 2018. Patients were divided into 2 groups based on pathology results: serosal invasion (stage T4a) and intact serosa (stages T1–T3). Cutoff values, the diagnostic efficacy of IC in the perigastric fat tissue, and the perigastric fat tissue/tumor (P/T) ratio were determined.

Results

Among the 41 patients, 22 had stage T4a gastric cancer and 19 patients had gastric cancer with a stage lower than T4a. The mean IC of perigastric fat tissue and the P/T ratio were significantly higher in patients with serosal invasion than in those with intact serosa (P < 0.001). During the arterial phase, the area under the curve (AUC) was 0.915 and 0.854 for the IC of perigastric fat tissue and the P/T ratio, respectively. During the venous phase, the AUC was 0.890 and 0.876 for the IC of perigastric fat tissue and the P/T ratio, respectively.

Conclusion

The IC in the perigastric fat tissue seems to be a reliable indicator for serosal invasion of gastric cancer.

Preoperative T staging of colon cancer using CT colonography with multiplanar reconstruction: new diagnostic criteria based on "bordering vessels"

PURPOSE

Preoperative T staging of colon cancer, in particular, for distinguishing T3 from T2 and T4, has been a challenge. The aim of this study was to evaluate newly developed criteria for preoperative T staging of colorectal cancer using computed tomography colonography (CTC) with multiplanar reconstruction (MPR), based on the spatial relationship of tumors and "bordering vessels," that is, marginal vessels that are detectable by multi-detector row CT with MPR.

METHODS

A total of 172 patients with colon and upper rectal cancer who underwent preoperative CTC and surgery between August 2011 and September 2013 were included. Preoperative T staging using the new criteria was performed prospectively and compared with pathologic results.

RESULTS

Sensitivity, specificity, and accuracy of T staging by CTC using the new criteria were 63%, 80%, and 77% for T2 (n = 30); 72%, 94%, and 81% for T3 (n = 95); and 79%, 99%, and 97% for T4a (n = 14), respectively. Positive predictive value for T3 was 93%, indicating that a T3 diagnosis by CTC is precise. In addition, negative predictive value for pathological T4a was 98%, indicating that a "not T4a" diagnosis by CTC is also precise.

CONCLUSIONS

Our newly developed criteria are useful for preoperative T staging, particularly for distinguishing T3 from T2 and T4.

Dual Energy Spectral CT Imaging in the assessment of Gastric Cancer and cell proliferation: A Preliminary Study

Gastric cancer is one of the main diseases leading to cancer-related death. The recently introduced dual-energy spectral CT (DEsCT), allows to obtain many quantitative measurements from iodine-based material decomposition (MD) images, which contribute to improve the accuracy of staging of GC comparing to multidetector spiral CT. And Ki-67 is a well-recognized nuclear antigen-specific biomarker reflecting cellular proliferation for estimating growth fractions of various tumor types. In the present study we analyzed the features of quantitative measurements (the curve slope (λ_HU), IC, normalized iodine concentrations (NIC)) obtained from DEsCT and levels of Ki-67 protein expression. We demonstrated that the values between advanced gastric cancer (AGC) and early gastric cancer (EGC) were significantly different both in venous phase (VP) and delayed phase (DP). The values of different level of Ki-67 expression grade were significantly different both in VP and DP. The rank correlation analysis between Ki-67 grade and IC, NIC and λ_HU values showed significantly positive correlation in VP and DP. These results suggested that quantitative parameters (IC, NIC and λ_HU) in dual-energy CT imaging can be used to differentiate EGC from AGC, and have significantly positive correlation with Ki-67 antigen expression levels in gastric cancer for indicating tumor cellular proliferation.

T and N Staging of Gastric Cancer Using Dual-Source Computed Tomography

AIM

This study is aimed at comparing gastric cancer T and N staging between virtual monochromatic energy images and fusion images generated by dual-source computed tomography (DSCT) dual-energy mode data acquisition prospectively while measuring the iodine concentration of gastric cancer and lymph nodes at different T and N stages from iodine map retrospectively.

METHODS

A total of 71 patients (50 males and 21 females; mean age: 59 ± 11 years) confirmed with gastric cancer by endoscopic biopsy with no neoadjuvant chemotherapy were enrolled for the CT examination before surgeries. The preoperative T and N staging results were compared between groups with pathological results as the gold standard. The iodine concentrations of the gastric lesions and LNs were measured on the iodine-based material decomposition images. All iodine concentration values were normalized against those in the abdominal aorta and defined as normalized iodine concentration (nIC) values. The short axis length of LNs and nIC values were statistically analyzed.

RESULTS

Group A was better than group B for T3 and T4 staging. No statistically significant difference in the overall accuracies for N staging was found between groups. For the late arterial and delayed phases, T3 and T4 nIC values of the extraserosal adipose tissue showed statistically significant differences. The nIC values between N0 and Nm (N1-N3) showed statistically significant differences in the portal phase only.

CONCLUSIONS

T3 and T4 nIC values of the extraserosal adipose tissue showed statistically significant differences. Hence, dual-source CT may be helpful in the differential diagnosis between T3 and T4.

Gastric Adenocarcinoma: A Multimodal Approach

Despite its declining incidence, gastric cancer (GC) remains a leading cause of cancer-related deaths worldwide. A multimodal approach to GC is critical to ensure optimal patient outcomes. Pretherapy fine resolution contrast-enhanced cross-sectional imaging, endoscopic ultrasound and staging laparoscopy play an important role in patients with newly diagnosed ostensibly operable GC to avoid unnecessary non-therapeutic laparotomies. Currently, margin negative gastrectomy and adequate lymphadenectomy performed at high volume hospitals remain the backbone of GC treatment. Importantly, adequate GC surgery should be integrated in the setting of a multimodal treatment approach. Treatment for advanced GC continues to expand with the emergence of additional lines of systemic and targeted therapies.

Gastric Cancer: Preoperative TNM Staging With Individually Adjusted Computed Tomography Scanning Phase

OBJECTIVE

The aim of this study was to evaluate test bolus scan technology on preoperative diagnostic performance, vascular enhancement, and artery visualization for gastric cancer.

METHODS

The institutional review board approved this study. Fifty-four patients in protocol 1 were resigned to a fixed delay time scan method, and their images were obtained in the late arterial phase (AP) and portal venous phase (PP), with start delays of 40 and 70 seconds, respectively. Fifty-six patients in protocol 2 had undergone the test bolus method first and received the time to peak enhancement of the aorta. Their images were obtained in the AP and PP with start delays in the time to peak enhancement and 20 seconds after the AP, respectively. Two radiologists performed consensus interpretation of the preoperative TNM staging, vascular enhancement, tumor contrast-to-noise ratio (CNR) and artery visualization between the 2 protocols.

RESULTS

There is no significant difference in the T, N, and M staging diagnostic accuracy between the protocols (P = 0.41, P > 0.99, and P = 0.34, respectively). For serosa-negative (T1, T2, and T3) tumors, the diagnostic accuracy obtained with protocol 2 was superior to that obtained with protocol 1 (P = 0.04). Protocol 2 was superior for perigastric vessel enhancement (left gastric artery, right gastroepiploic artery, and splenic artery; P < 0.001, P < 0.001, and P = 0.001, respectively). The stomach-to-tumor CNR during the PP of protocol 2 was significantly higher than that during either the AP or PP of protocol 1 (P = 0.004 and P = 0.001, respectively). The mean rankings of the artery visualization were significantly higher with protocol 2 than with protocol 1 (P < 0.001).

CONCLUSIONS

The dual-phase scan with test bolus technology could improve the tumor CNR and had high staging accuracy for serosa-negative tumors as well as high perigastric artery enhancement, yielding satisfactory artery visualization for diagnosis.

Quantification of the Iodine Content of Perigastric Adipose Tissue by Dual-Energy CT: A Novel Method for Preoperative Diagnosis of T4-Stage Gastric Cancer

This study investigated the utility of quantifying iodine concentration (IC) in perigastric adipose tissue, using dual-energy computed tomography (DECT), for the detection of T4a-stage gastric cancer. Fifty-four patients with gastric cancer were enrolled at the Fourth Hospital of Hebei Medical University between January and June 2013. Patients were imaged preoperatively with conventional computed tomography (CT) scans and DECT, and the IC in perigastric fat adjacent to the tumor calculated from arterial phase (AP) and portal venous phase (PVP) images. The patients subsequently received surgical treatment (gastrectomy), and histologic analysis of resected specimens was used as a ‘gold standard’ reference for cancer staging. Receiver operating characteristic (ROC) curve analysis was employed to assess the utility of DECT for identifying T4a-stage gastric cancer, with optimal IC thresholds determined from the area under the ROC curve (AUC). Postoperative histology revealed that 32 patients had serosal invasion (group A), and 22 did not (group B). The accuracy of conventional CT for distinguishing stage T4 from non-T4 stages was 68.5% (37/54). IC was significantly higher in group A than in group B (AP: 0.60±0.34 vs. 0.09±0.19 mg/mL, p<0.001; PVP: 0.83±0.41 vs. 0.27±0.21 mg/mL, p<0.001). The sensitivity, specificity and AUC for detecting serosal invasion were 77.1%, 79.2% and 0.89 at an IC threshold of 0.25 mg/mL for AP images; and 80.0%, 79.2% and 0.90 at an IC threshold of 0.45 mg/mL for PVP images. These results indicated that Iodine quantification in perigastric fat using DECT is an accurate method for detecting serosal invasion by gastric cancer.

Diagnostic Value of Multidetector CT and Its Multiplanar Reformation, Volume Rendering and Virtual Bronchoscopy Postprocessing Techniques for Primary Trachea and Main Bronchus Tumors

Purpose

To evaluate the diagnostic value of multidetector CT (MDCT) and its multiplanar reformation (MPR), volume rendering (VR) and virtual bronchoscopy (VB) postprocessing techniques for primary trachea and main bronchus tumors.

Methods

Detection results of 31 primary trachea and main bronchus tumors with MDCT and its MPR, VR and VB postprocessing techniques, were analyzed retrospectively with regard to tumor locations, tumor morphologies, extramural invasions of tumors, longitudinal involvements of tumors, morphologies and extents of luminal stenoses, distances between main bronchus tumors and trachea carinae, and internal features of tumors. The detection results were compared with that of surgery and pathology.

Results

Detection results with MDCT and its MPR, VR and VB were consistent with that of surgery and pathology, included tumor locations (tracheae, n = 19; right main bronchi, n = 6; left main bronchi, n = 6), tumor morphologies (endoluminal nodes with narrow bases, n = 2; endoluminal nodes with wide bases, n = 13; both intraluminal and extraluminal masses, n = 16), extramural invasions of tumors (brokethrough only serous membrane, n = 1; 4.0 mm—56.0 mm, n = 14; no clear border with right atelectasis, n = 1), longitudinal involvements of tumors (3.0 mm, n = 1; 5.0 mm—68.0 mm, n = 29; whole right main bronchus wall and trachea carina, n = 1), morphologies of luminal stenoses (irregular, n = 26; circular, n = 3; eccentric, n = 1; conical, n = 1) and extents (mild, n = 5; moderate, n = 7; severe, n = 19), distances between main bronchus tumors and trachea carinae (16.0 mm, n = 1; invaded trachea carina, n = 1; >20.0 mm, n = 10), and internal features of tumors (fairly homogeneous densities with rather obvious enhancements, n = 26; homogeneous density with obvious enhancement, n = 1; homogeneous density without obvious enhancement, n = 1; not enough homogeneous density with obvious enhancement, n = 1; punctate calcification with obvious enhancement, n = 1; low density without obvious enhancement, n = 1).

Conclusion

MDCT and its MPR, VR and VB images have respective advantages and disadvantages. Their combination could complement to each other to accurately detect locations, natures (benignancy, malignancy or low malignancy), and quantities (extramural invasions, longitudinal involvements, extents of luminal stenoses, distances between main bronchus tumors and trachea carinae) of primary trachea and main bronchus tumors with crucial information for surgical treatment, are highly useful diagnostic methods for primary trachea and main bronchus tumors.

Multidetector computed tomography in the preoperative staging of gastric adenocarcinoma

Objective

To evaluate the role of multidetector computed tomography in the preoperative investigation of tumor invasion depth and lymph node and metastatic involvement according to the TNM classification, in patients with gastric adenocarcinoma.

Materials and Methods

Fifty-four patients with biopsy-confirmed gastric cancer underwent preoperative staging with 64-channel multidetector computed tomography. Two independent radiologists analyzed the images and classified the findings. Sensitivity, specificity, accuracy and overall accuracy were calculated for each observer. The interobserver agreement was also evaluated.

Results

The accuracy in the classification of categories T ranged from 74% to 96% for observer 1 and from 80% to 92% for observer 2. The overall accuracy was 70% for both observers. The weighted kappa index was 0.75, consistent with a significant interobserver agreement. The accuracy in the classification of lymph node involvement (category N) ranged from 55% to 79% for observer 1 and from 73% to 82% for observer 2. The evaluation of metastatic involvement showed an overall accuracy of 89.6% for both observers.

Conclusion

64-channel multidetector computed tomography demonstrated clinically relevant accuracy in the preoperative staging of gastric adenocarcinoma as regards invasion depth (T category) and metastatic involvement (M category).

CT volumetry for gastric carcinoma: association with TNM stage

OBJECTIVES

We evaluated the feasibility of performing CT volumetry of gastric carcinoma (GC) and its correlation with TNM stage.

METHODS

This institutional review board-approved retrospective study was performed on 153 patients who underwent a staging CT study for histologically confirmed GC. CT volumetry was performed by drawing regions of interest including abnormal thickening of the stomach wall. Reproducibility of tumour volume (Tvol) between two readers was assessed. Correlation between Tvol and TNM/peritoneal staging derived from histology/surgical findings was evaluated using ROC analysis and compared with CT evaluation of TNM/peritoneal staging.

RESULTS

Tvol was successfully performed in all patients. Reproducibility among readers was excellent (r = 0.97; P = 0.0001). The median Tvol of GC showed an incremental trend with T-stage (T1 = 27 ml; T2 = 32 ml; T3 = 53 ml and T4 = 121 ml, P < 0.01). Tvol predicted with good accuracy T-stage (≥T2:0.95; ≥T3:0.89 and T4:0.83, P = 0.0001), M-stage (0.87, P = 0.0001), peritoneal metastases (0.87, P = 0.0001) and final stage (≥stage 2:0.89; ≥stage 3:0.86 and stage 4:0.87, P = 0.0001), with moderate accuracy for N-stage (≥N1:0.75; ≥N2:0.74 and N3:0.75, P = 0.0001). Tvol was significantly (P < 0.05) more accurate than standard CT staging for prediction of T-stage, N3-stage, M-stage and peritoneal metastases.

CONCLUSION

CT volumetry may provide useful adjunct information for preoperative staging of GC.

KEY POINTS

CT volumetry of gastric carcinoma is feasible and reproducible. Tumour volume <19.4 ml predicts T1-stage gastric cancer with 91% sensitivity and 100% specificity (P = 0.0001). Tumour volume >95.7 ml predicts metastatic gastric cancer with 87% sensitivity and 78.5% specificity (P = 0.0001). CT volumetry may be a useful adjunct for staging gastric carcinoma.

Gastric carcinoma: imaging diagnosis, staging and assessment of treatment response

Gastric carcinoma (GC) is one of the most common causes of cancer-related death worldwide. Surgical resection is the only cure available and is dependent on the GC stage at presentation, which incorporates depth of tumor invasion, extent of lymph node and distant metastases. Accurate preoperative staging is therefore essential for optimal surgical management with consideration of preoperative and/or postoperative chemotherapy. Multidetector computed tomography (MDCT) with its ability to assess tumor depth, nodal disease and metastases is the preferred technique for staging GC. Endoscopic ultrasonography is more accurate for assessing the depth of wall invasion in early cancer, but is limited in the assessment of advanced local or stenotic cancer and detection of distant metastases. Magnetic resonance imaging (MRI), although useful for staging, is not proven to be effective. Positron emission tomography (PET) is most useful for detecting and characterizing distant metastases. Both MDCT and PET are useful for assessment of treatment response following preoperative chemotherapy and for detection of recurrence after surgical resection. This review article discusses the usefulness of imaging modalities for detecting, staging and assessing treatment response for GC and the potential role of newer applications including CT volumetry, virtual gastroscopy and perfusion CT in the management of GC.

Computed tomography of gastrohepatic ligament involvement by gastric carcinoma

PURPOSE

This study was aimed to analyze the contrast-enhanced CT features of gastrohepatic ligament (GHL) involvement in gastric carcinoma (GC) and to evaluate the influence of GHL on the spread of GC correlating with the anatomic bases.

METHODS

CT scans of 41 patients known to have GC and GHL involvement were reviewed retrospectively for the primary tumor and the GHL abnormalities, as well as the role GHL played in the spread of GC. Emphasis was placed on direct invasion, lymph node metastasis, and GHL seeding. The relationship between the accompanying ascites and the different pattern of the GHL involvement were also evaluated statistically.

RESULTS

CT features of the GHL abnormalities caused by GC could be summarized as follows: (a) direct invasion (34.1%, 14 of 41), which was visualized as a regional (nine of 14) or diffuse mass (five of 14) in the GHL; (b) GHL seeding (26.8%, 11 of 41), which consists of ''smudged'' appearance (eight of 11), nodular infiltration (two of 11) and "GHL caking" (one of 11); (c) lymph node metastasis (63.4%, 26 of 41), including enlargement of lymph nodes (22 of 26) and cystic lesion (four of 26). We also found direct extension of GC into the transverse fissure and/or the liver via the GHL in three patients. Ascites, which was found in ten patients, seemed to be associated with the pattern of seeding involvement.

CONCLUSIONS

GHL can be invaded by GC through several patterns and contrast-enhanced CT scan plays an important role in detecting GHL involvement in GC, which has a variety of CT manifestations. GHL may also serve as a potential conduit for the predictable spread of GC into the neighboring organs such as the liver.

Gastric cancer staging with dual energy spectral CT imaging

Purpose

To evaluate the clinical utility of dual energy spectral CT (DEsCT) in staging and characterizing gastric cancers.

Materials and Methods

96 patients suspected of gastric cancers underwent dual-phasic scans (arterial phase (AP) and portal venous phase (PP)) with DEsCT mode. Three types of images were reconstructed for analysis: conventional polychromatic images, material-decomposition images, and monochromatic image sets with photon energies from 40 to 140 keV. The polychromatic and monochromatic images were compared in TNM staging. The iodine concentrations in the lesions and lymph nodes were measured on the iodine-based material-decomposition images. These values were further normalized against that in aorta and the normalized iodine concentration (nIC) values were statistically compared. Results were correlated with pathological findings.

Results

The overall accuracies for T, N and M staging were (81.2%, 80.0%, and 98.9%) and (73.9%, 75.0%, and 98.9%) determined with the monochromatic images and the conventional kVp images, respectively. The improvement of the accuracy in N-staging using the keV images was statistically significant (p<0.05). The nIC values between the differentiated and undifferentiated carcinoma and between metastatic and non-metastatic lymph nodes were significantly different both in AP (p = 0.02, respectively) and PP (p = 0.01, respectively). Among metastatic lymph nodes, nIC of the signet-ring cell carcinoma were significantly different from the adenocarcinoma (p = 0.02) and mucinous adenocarcinoma (p = 0.01) in PP.

Conclusion

The monochromatic images obtained with DEsCT may be used to improve the N-staging accuracy. Quantitative iodine concentration measurements may be helpful for differentiating between differentiated and undifferentiated gastric carcinoma, and between metastatic and non-metastatic lymph nodes.

Pilot feasibility study of neoadjuvant chemoradiotherapy with S-1 in patients with locally advanced gastric cancer featuring adjacent tissue invasion or JGCA bulky N2 lymph node metastases

BACKGROUND

To improve the prognosis of locally advanced gastric cancer, clinical trials of neoadjuvant chemotherapy (NAC) are being performed. Although neoadjuvant chemoradiotherapy (NACRT) generally achieves superior local tumor control to NAC, its efficacy for locally advanced gastric cancers remains unclear. Therefore, a prospective trial was conducted to explore the feasibility and safety of NACRT with oral S-1 in a series of cases.

METHODS

Patients who had Japanese Gastric Cancer Association (JGCA) cStage IIIB gastric cancer were enrolled onto this study and received oral S-1 (65 mg/m(2)/day) administration and 50-Gy radiotherapy followed by radical surgery. The primary end points were completion of therapy and safety.

RESULTS

Between October 2005 and September 2008, 12 eligible patients were enrolled. Two could not complete the chemotherapy because of grade 3 toxicity. R0 resections were performed in 11 patients (91.7 %) (95 % confidence interval 61.5-99.8). Although operative morbidity was observed in two cases, there were no postoperative deaths. A pathologic response was observed in 10 patients (83.3 %). In five (62.5 %) of eight gastric cancers with invasion to adjacent structures, microscopic tumor deposits were not found in the affected organs. The 3-year survival rate was 58.3 % during a median follow-up period of 36 months.

CONCLUSIONS

Although this study is preliminary, the present regimen seems to be feasible and safe as a treatment for locally advanced gastric cancers featuring adjacent tissue invasion or JGCA bulky N2 disease. This treatment approach should now be tested using the new tumor, node, metastasis staging system in a large clinical trial.

Uneven haustra on CT colonography: a clue for the detection of transperitoneal invasion from gastric cancer

Two patients with gastric carcinoma underwent CT colonography (CTC) for preoperative work-up. Although no obvious peritoneal nodules were seen on axial CT images, colonic wall deformities were noted on three-dimensional (3D) air images. Multiplanar-reformatted images revealed corresponding colonic wall thickening at the deformities, and in addition, dense cordlike structures connecting the primary gastric cancer and colonic wall thickening were also observed. In one patient, cordlike indurations consistent with peritoneal invasion were found to connect the primary gastric cancer, gastrocolic ligament, and transverse mesocolon during exploratory surgery, and in the other, colonic scars consistent with peritoneal invasion after chemotherapy were observed. These observations suggest that CTC could be of potential use for the differentiation of transperitoneal colonic invasion and gastric cancer.

Transverse mesocolon invasion in advanced gastric cancer: should we reconsider current T staging?

BACKGROUND

According to the AJCC/UICC TNM classification, T mesocolon invasion in AGC is classified as T2b or T3 according to the presence or the absence of serosa invasion. However, many authors have considered T mesocolon invasion in AGC as T4. This study was performed to evaluate the appropriate T stage for T mesocolon invasion in AGC.

MATERIALS AND METHODS

From 1996 to 2008, 90 patients underwent curative gastrectomy with T mesocolon excision at the authors' institute under the suspicion of T mesocolon invasion based on surgical findings and without pathologic invasion to any other organ. Histopathologic findings were reviewed to determine whether tumors had invaded the T mesocolon. Survival data of AGC patients registered in the SNUH database (N = 9998, from 1986 to 2007) was used as reference data for comparative purposes.

RESULTS

A total of 27 patients (30%) had proven histopathological invasion of the T mesocolon, and a significant difference in survival rates was found between these 27 and the remaining 63 (P = .012). As compared with the SNUH database population, the survival rate of T mesocolon invasion patients differed from those of T2b (P < .001) and T3 (P = .043) patients, but was similar to that of T4 patients (P = .218). Furthermore, for N1 stage patients, the survival rate differed from those of T2b (P = .001) and T3 (P = .046) patients, but was similar to that of T4 patients (P = .744).

CONCLUSIONS

The T stage of T mesocolon invasion in AGC should be revised to AJCC/UICC stage T4, because the survival rate of T mesocolon invasion AGC is lower than that of stage T2b or T3.

[Diagnostic imaging in oncology--evidence reviews for evidence based guidelines by the Agency of Quality for Medicine (ÄZQ)]

Within the context of the development of evidence-based oncology guidelines, the Agency for Quality in Medicine undertook evidence reviews for diagnostic imaging procedures. Systematic searches retrieved no randomised controlled trials, but only cohort studies and case series of mostly moderate quality. The identified studies provided only a restricted basis for the guideline recommendations as their validity was limited and only outcomes of diagnostic accuracy were examined. However, decision criteria for recommending diagnostic strategies significantly comprise judgements about required resources and availability of diagnostic imaging procedures. These criteria as well as patient out-comes were mostly implicit and should be explicated in future. In order to increase the relevance of evidence reviews for oncological diagnosis, high quality studies which examine resources and patient-centred outcomes for diagnostic strategies are required.

Peritoneal metastasis: detection with 16- or 64-detector row CT in patients undergoing surgery for gastric cancer

PURPOSE

To retrospectively measure the diagnostic performance of prospective computed tomographic (CT) results obtained by using 16- or 64-detector row scanners in the detection of peritoneal metastases (PMs) in patients with advanced gastric cancer.

MATERIALS AND METHODS

The institutional review board approved this retrospective study and waived the need to obtain patient consent. In 498 patients with gastric cancer (stage >or= T2) who were undergoing surgery, the presence of PM was prospectively rated as grade 0 (absent), grade 1 (equivocal), or grade 2 (present) on CT scans (0.67 or 2 mm thick) that were interpreted by interactively adjusting the viewing thickness and viewing plane. The CT readings were retrospectively compared with surgical and pathologic findings. In patients in whom the presence of PM was rated as grade 1 or less, factors predictive of PM were identified by testing variables, including patient and tumor characteristics, with univariate tests and multivariate logistic regression analysis.

RESULTS

Fifty-three patients (10.6%) had confirmed PM. When only grade 2 was considered to indicate a positive CT reading, sensitivity and specificity were 28.3% (15 of 53) and 98.9% (440 of 445), respectively. With the threshold of grade 1 or greater indicating a positive reading, sensitivity and specificity were 50.9% (27 of 53) and 96.2% (428 of 445), respectively. In the patients with grades of 1 or less, the significant factors predictive of PM were greater tumor size and T stage.

CONCLUSION

The sensitivity of PM detection is limited, even with modern CT techniques. In patients whose CT results are not definitely positive for PM, staging laparoscopy is still recommended if the aforementioned two predictive factors (greater tumor size and T stage) are suspected.